Anchor channel and method for producing an anchor channel

ABSTRACT

For stable anchoring of an anchor channel in concrete, an anchor, the anchor shank of which has a larger diameter than an anchor hole of a C-profile channel of the anchor channel, is inserted through the anchor hole from the inside, so that the anchor shank widens the anchor hole and holds the C-profile channel clamped on the anchor shank. An anchor head configured as a countersink head bears internally against a protrusion of the C-profile channel, and on the outer side of the C-profile channel knurling holds the anchor in addition to the clamped fit.

The invention relates to an anchor channel having the features of thepreamble of claim 1 and to a method for producing an anchor channelhaving the features of the preamble of claim 5.

Anchor channels are typically arranged sunk flush in a floor or a wallmade of concrete and serve for attaching articles, for example façadeelements, with the aid of, for example, hammerhead screws. “Sunk flush”means that the anchor channel is embedded in the concrete and one sideof the anchor channel is flush with a surface, for example of theconcrete. During the production of the floor or the like, the anchorchannels are embedded in the concrete on three sides. The anchorchannels typically have a C-profile channel, that is to say a squaretube profile or a rectangular tube profile with a continuouslongitudinal slot in a transverse centre of a side which is alsoreferred to herein as the “upper side”. In a transverse centre of anopposite side, which is also referred to as the “underside” herein, theC-profile channels typically have round and/or elongate holes as anchorholes. Anchor channels are typically made or extruded from sheet steelor generally sheet metal, but materials other than metal are alsopossible. The upper side of the C-profile channel need not be located atthe top nor does its underside need to be located at the bottom, butrather the upper side is the side having the continuous longitudinalslot and the underside is the opposite side.

German utility model DE 88 15 267 U1 discloses an anchor channel havinga C-profile channel and an anchor which has been inserted from theinside through an anchor hole in an underside of the C-profile channelso that an anchor shank of the anchor projects outwards on the undersideof the C-profile channel. The anchor shank has a thread at one end and afrustoconical countersink head as anchor head at another end. TheC-profile channel has a hollow-frustoconical protrusion projectingoutwards from the underside and surrounding the anchor hole, insidewhich protrusion the anchor head lies on the inner side of the C-profilechannel. Adjoining the anchor head, the anchor shank has acircumferential groove in which a circumferential ridge in the anchorhole of the C-profile channel engages, so that the anchor is held in theanchor hole of the C-profile channel. An anchor foot in the form of anapertured disc is screwed onto the thread at the end of the anchor shankremote from the C-profile channel, which foot gives the anchor purchasein the concrete. By means of the anchor or preferably a plurality ofanchors distributed over a length of the C-profile channel, theC-profile channel can be anchored in, for example, concrete.

The problem of the invention is to propose an anchor channel and amethod for producing an anchor channel of the kind described at thebeginning having modified attachment of an anchor.

That problem is solved according to the invention by the features ofclaims 1 and 5. The anchor channel according to the invention has aC-profile channel having an anchor hole in a side of the C-profilechannel referred to herein as the underside and an anchor which has beeninserted through the anchor hole from the inside. The anchor hole ispreferably located in a transverse centre of the underside of theC-profile channel. The anchor has an anchor head and an anchor shank.“Inserted from the inside” means that the anchor head is located in theC-profile channel, that is to say located on an inner side of theunderside of the C-profile channel, and the anchor shank projectsoutwards from the underside of the C-profile channel through the anchorhole. In particular, the anchor head bears against the inner side of theunderside of the C-profile channel. The underside of the anchor channelcan have an outwardly projecting protrusion matched to a shape of theanchor head, against or inside the inner side of which protrusion theanchor head bears or lies. The anchor shank, together with the C-profilechannel, is intended to be embedded in concrete or the like in order toachieve a good hold of the C-profile channel or the anchor channel inthe concrete. For that purpose, an anchor foot adjoins the anchor shankat the end opposite the anchor head. By virtue of the anchor foot, theanchor is wider in cross-section at that end.

According to the invention, the anchor shank has knurling spaced apartfrom the anchor head, the spacing between the knurling and the anchorhead especially corresponding to a wall thickness of the underside ofthe C-profile channel at a hole rim of the anchor hole. A cross-sectionof the anchor shank is the same on both sides of the knurling and isespecially circular and the hole rim of the anchor hole engages betweenthe anchor head and the knurling, so that the anchor is held by theknurling against movement of the anchor out of the anchor hole throughthe inner side of the C-profile channel, a limited holding force whichholds the anchor against falling out of the C-profile channel and whileit is being embedded in the concrete being sufficient. The inventiondoes not exclude the anchor from being pulled out or pushed out of theanchor hole by a force greater than the holding force.

An advantage of the invention is the simple attachment of the anchor tothe C-profile channel with a holding force sufficient for theconcreting. To prevent removal of the C-profile channel from the anchor,the anchor head holds the C-profile channel in its inner side. By meansof the anchor or preferably a series of anchors arranged over a lengthof the C-profile channel it is possible to achieve a good hold of theC-profile channel, or the anchor channel as a whole, in concrete or thelike. The knurling is very easy to produce and is accordingly a simpleway of securing the anchor against movement towards the inner side ofthe C-profile channel.

In a preferred embodiment of the invention, the hole rim of the anchorhole of the C-profile channel is seated clamped between the anchor headand the knurling. In particular, the anchor hole has a cross-sectionwhich effects the clamping on the anchor shank between the anchor headand the knurling at two oppositely located circumferential locations orat more than two circumferential locations distributed uniformly ornon-uniformly around the circumference or continuously around the entirecircumference. As a result, independently of being held interlockinglyby the knurling, the anchor shank of the anchor is additionally held inthe anchor hole of the C-profile channel by frictional engagement.

An embodiment of the invention provides a countersink head as anchorhead, that is to say an anchor head having a frustoconical underside,and a protrusion that projects outwards from the C-profile channel andsurrounds the anchor hole. The underside of the anchor head facestowards the anchor shank. The protrusion of the C-profile channel ispreferably hollow-frustoconical to match the underside of the anchorhead, and the anchor head bears against the protrusion or lies insidethe protrusion on the inner side of the anchor channel.

In a preferred embodiment of the invention, the C-profile channel has aslot, especially a continuous longitudinal slot, preferably in atransverse centre of a side opposite the underside having the anchorhole, which side is referred to herein as the upper side. Through theslot, for example a hammerhead screw, which is not part of theinvention, for attachment an article to the anchor channel can beintroduced into the C-profile channel thereof. The anchor head of theanchor of the anchor channel according to the invention is narrower andlonger than the slot of the C-profile channel is wide, so that theanchor, including the anchor head, can be introduced through the slotinto the C-profile channel and the anchor shank can be inserted throughthe anchor hole in the underside of the C-profile channel.

For the production of an anchor channel especially of the kind describedabove, which has a C-profile channel having an anchor hole and an anchorhaving an anchor head and an anchor shank, according to the inventionthe anchor or rather the anchor shank is inserted through the anchorhole from the inside, so that the anchor shank emerges from theC-profile channel through the anchor hole and projects outwards from theC-profile channel from the underside thereof. The anchor head is locatedin the C-profile channel; preferably it bears against an inner side ofthe underside of the C-profile channel. The anchor head in the C-profilechannel prevents the anchor from being withdrawable outwards out of theC-profile channel or, conversely, the C-profile channel from beingremovable from the anchor over the anchor head.

Before the anchor shank is inserted through the anchor hole, thediameter of the anchor hole is smaller than a maximum diameter of theanchor shank and during insertion of the anchor shank is at leasttemporarily widened by the anchor shank. In the case of non-circularcross-sections, the “diameter” is to be understood as being the diameterof an inscribed circle in the case of the anchor hole and of acircumscribed circle in the case of the anchor shank. The diameter canbe constant over the length of the anchor shank. If the anchor shankhas, in the region of the anchor hole, a larger diameter than theoriginal diameter of the anchor hole, this especially results in aclamped fit between the hole rim of the anchor hole in the C-profilechannel and the anchor shank of the anchor. The hole rim of the anchorhole can be in continuous clamping contact with the inserted anchorshank without interruption in the circumferential direction, or it bearsclampingly against the anchor shank at two oppositely locatedcircumferential locations or at more than two circumferential locationsdistributed uniformly or non-uniformly around the circumference. If theanchor shank has, in the region of the anchor hole, a smaller diameterthan the anchor hole, a fit having a greater or lesser degree of play isobtained. The location having the maximum diameter of the anchor shanknevertheless ensures that the anchor shank is held by interlockingengagement.

An embodiment of the invention provides that the anchor has acounter-bearing that protrudes beyond a circumference of the anchorshank, which counter-bearing overlaps the hole rim of the anchor hole onan outer side of the C-profile channel and thereby enables the anchor orthe anchor shank to be held by interlocking engagement in the anchorhole of the C-profile channel so as to prevent movement of the anchorout through the inner side of the C-profile channel, that is to sayanchor head first. In particular, the counter-bearing forms the maximumdiameter of the anchor shank.

In particular, the knurling described hereinabove, which is arranged onthe anchor shank spaced apart from the anchor head, forms thecounter-bearing. Alternatives to the knurling are one or more lugs orbeads projecting outwards from the anchor shank. Circumferentialcounter-bearings are also possible. This list serves to provide anoverview of possible ways of implementing the counter-bearing but theinvention is not limited to the examples given. The hole rim of theanchor hole of the C-profile channel engages between the anchor head andthe knurling or the counter-bearing.

Preferably, prior to the insertion of the anchor hole the diameter ofthe anchor hole is smaller than the diameter of the anchor shank betweenthe anchor head and the counter-bearing. As a result, the anchor can beheld both clamped by the hole rim and interlockingly by thecounter-bearing. Spaced apart from the anchor head, i.e. on a side ofthe counter-bearing or knurling remote from the anchor head, the anchorshank can have a smaller diameter

As explained above, in configurations of the anchor channel according tothe invention the C-profile channel has on its underside an outwardlyprojecting protrusion that surrounds the anchor hole, against or insidethe inner side of which protrusion the anchor head bears or lies. Theprotrusion can have been or can be formed or generally produced prior tothe insertion of the anchor shank, for example by plastic deformation ofthe underside of the C-profile channel in a region surrounding theanchor hole. An embodiment of the method according to the inventionprovides that the protrusion is formed by the anchor head of the anchor.For that purpose, at the end of the insertion of the anchor shank, theanchor head, or rather its underside, is pressed from the inside againstthe inner side of the underside of the C-profile channel, so that theregion of the underside of the C-profile channel that surrounds theanchor hole is shaped to form the protrusion projecting outwards on theunderside of the C-profile channel. The deformation of the region of theunderside of the C-profile channel that surrounds the anchor hole bymeans of the anchor head can be plastic and/or resilient. The anchorhead forms as it were a depression on the inner side of the underside ofthe C-profile channel, against or inside which depression the anchorhead or its underside preferably exactly fits.

The features and combinations of features, configurations andembodiments of the invention mentioned above in the description, as wellas the features and combinations of features mentioned below in thedescription of the Figures and/or shown in a Figure, can be employed notonly in the particular combination defined or shown in each case, butalso in basically any other combinations or on their own. Configurationsof the invention that do not have all features of a dependent claim arepossible. It is also possible for individual features of a claim to bereplaced by other disclosed features or combinations of features.Configurations of the invention are possible that do not have allfeatures of the exemplary embodiment(s) but have in principle any partof the characterised features of an exemplary embodiment, optionally incombination with one, some or all features of one or more furtherexemplary embodiments.

The invention is explained in greater detail below with reference to anexemplary embodiment shown in the drawing, wherein:

FIG. 1 shows a cross-section through an anchor channel according to theinvention;

FIG. 2 is an end view of an anchor head of an anchor of the anchorchannel from FIG. 1 ;

FIG. 3 shows a cross-section through a C-profile channel of the anchorchannel from FIG. 1 ;

FIG. 4 shows punching an anchor hole in an underside of the C-profilechannel from FIG. 3 ;

FIG. 5 shows forming a protrusion that surrounds the anchor hole on theunderside of the C-profile channel from FIG. 2 ;

FIG. 6 shows a longitudinal section through the anchor channel from FIG.1 ;

FIG. 7 shows an anchor foot of the anchor of the anchor channel fromFIG. 1 ;

FIG. 8 shows an alternative anchor foot of the anchor of the anchorchannel from FIG. 1 ; and

FIG. 9 shows a cross-section through a second embodiment of an anchorchannel according to the invention.

The anchor channel 1 according to the invention shown in FIG. 1 has aC-profile channel 2 and an anchor 3. The C-profile channel 2 is, forexample, extruded or formed from sheet metal. It has a square orrectangular cross-section and a continuous longitudinal slot 4 in atransverse centre of a side of the C-profile channel 2 referred toherein as the upper side 5 and a series of circular anchor holes 6,spaced apart in the longitudinal direction of the C-profile channel 2,in a transverse centre of a side of the C-profile channel 2 locatedopposite the upper side 5 having the longitudinal slot 4 and referred toherein as the underside 7.

The anchor 3 has an anchor shank 8, which is cylindrical in theexemplary embodiment, having an anchor head 9 at one end. In end view(FIG. 2 ), the anchor head 9 has an elongate shape with two mutuallyparallel longitudinal sides 10 and arcuately curved transverse sides 11.The anchor head 9 is longer and narrower than the longitudinal slot 4 inthe upper side 5 of the C-profile channel 2 is wide, so that the anchorhead 9 when aligned in the longitudinal direction of the C-profilechannel 2 can be introduced into the C-profile channel 2 through thelongitudinal slot 4. An underside 12 of the anchor head 9 facing towardsthe anchor shank 8 is frustoconical in the exemplary embodiment, forwhich reason the anchor head 9 can also be thought of as a countersinkhead.

Spaced apart from the anchor head 9 by a distance corresponding to athickness of the underside 7 of the C-profile channel 2 at a hole rim ofthe anchor hole 6, the anchor 3 has knurling 13 on its anchor shank 8,which knurling can generally also be thought of as a counter-bearing 14protruding on a circumference of the anchor shank 9. The knurling 13 canbe parallel knurling, left-hand or right-hand knurling, cross-knurlingand basically as desired. A counter-bearing 14 other than knurling thatprotrudes on the circumference of the anchor shank 9 is also possible(not shown). The knurling 13 is the location of the maximum diameter ofthe anchor shank 9. Since the cross-section in this region is notcircular, the “diameter” here means the diameter of a circlecircumscribing the knurling 13. That diameter is larger than thediameter of the remainder of the anchor shank 8.

The anchor 3 has been or is inserted through the anchor hole 6 in theunderside 7 of the C-profile channel 2 from the inside, so that theanchor shank 8 projects outwards from the underside 7 of the C-profilechannel 2 having the anchor hole 6 and the anchor head 9 is located inthe C-profile channel 2. Preferably the anchor head 9 bears internallyagainst the underside 7 of the C-profile channel 2. “From the inside”means that the anchor 3 is passed, anchor shank 8 first, through thelongitudinal slot 4 in the upper side 5 of the C-profile channel 2 andthrough the anchor hole 6 in the underside 7 of the C-profile channel 2until the anchor head 9 is located in the C-profile channel 2 and, asdescribed, preferably bears internally against the underside 7 thereofand the anchor shank 8 projects outwards from the underside 7 of theC-profile channel 2.

Prior to the insertion of the anchor shank 8, a diameter of the anchorhole 6 is smaller than a diameter of the anchor shank 8 between theanchor head 9 and the knurling 13, the anchor shank 8 in the exemplaryembodiment having the same diameter on both sides of the knurling 13.During insertion, the anchor shank 8 widens the anchor hole 6, the holerim of the anchor hole 6 slightly narrowing again resiliently once theknurling 13 has passed, so that the hole rim of the anchor hole 6 of theC-profile channel 2 has a clamped fit on the anchor shank 8. Inaddition, the anchor head 9 holds the anchor shank 8 in an axialdirection thereof and the knurling 13 forming the counter-bearing 14holds the anchor shank 8 in an opposite axial direction in the underside7 of the C-profile channel 2 by interlocking engagement. The hole rim ofthe anchor hole 6 of the C-profile channel 2 engages between the anchorhead 9 and the knurling 13 of the anchor 3.

As FIG. 3 shows, the underside 7 of the C-profile channel 2 of theanchor channel 1 according to the invention is originally, that is tosay prior to the insertion of the anchor shank 8, flat. The anchorhole(s) 6 are, for example, drilled or, as shown in FIG. 4 , punchedwith a punch 15 which can be, for example, cylindrical or, in theexemplary embodiment, conical. Prior to the insertion of the anchorshank 8, the anchor hole 6 has approximately 0.7 times the diameter ofthe anchor shank 8 outside the knurling 13.

At a larger-diameter end, the punch 15 has a frustoconical annularshoulder as deforming shoulder 16 which is pushed through thelongitudinal slot 4 of the C-profile channel 2 against the inner side ofthe underside 7 of the C-profile channel 2, so that an outwardlyprojecting, hollow-frustoconical protrusion 17 that surrounds the anchorhole 6 is formed on the underside 7 of the C-profile channel 2 (FIG. 5). For punching the anchor hole 6 and forming the protrusion 17, theunderside 7 of the C-profile channel 2 is supported on a die 18 having ahole 19 for passage of the punch 15 and a frustoconical depression 20for the protrusion 17 of the C-profile channel 2. Although forming theprotrusion 17 widens the anchor hole 6, the anchor hole 6 is originallysufficiently narrow that, even after the protrusion 17 has been formed,its diameter is still smaller than the diameter of the anchor shank 8outside the knurling 13, so that the anchor shank 8 widens the anchorhole 6 during insertion and holds the C-profile channel 2 clamped on theanchor shank 8.

As described hereinabove, the anchor shank 8 of the anchor 3 is passedthrough the anchor hole 6 of the C-profile channel 2 of the anchorchannel 1 according to the invention from the inside, so that the anchorshank 8 projects outwards from the underside 7 of the C-profile channel2 and on the inner side of the underside 7 of the C-profile channel 2the frustoconical underside 12 of the anchor head 9 bears against orlies inside the protrusion 17 that surrounds the anchor hole 6, as shownin cross-section in FIG. 1 and in longitudinal section in FIG. 6 .

After the insertion of the anchor shank 8 through the anchor hole 6 ofthe C-profile channel 2, an anchor foot 21, 22 is provided on an end ofthe anchor shank 8 remote from the anchor head 9 and the C-profilechannel 2. The anchor head 9 can be formed integrally with the anchorshank 8, for example by upsetting of the anchor shank 8, or can bewelded or screwed to the anchor shank 8. FIG. 7 shows a frustoconicalanchor foot 21 formed on the anchor shank 8 by upsetting, and FIG. 8shows a nut as anchor foot 22 which has been or is screwed onto a thread23 of the anchor shank 8. The anchor foot 21, 22 can have a differentshape from that shown and described and/or can be provided on the anchorshank 8 in a different way from that described. The cross-section of theanchor 3 is made wider by the anchor foot 21, 22 so that the anchor isable to find good purchase in the concrete.

In the case of the anchor channel 1 according to the invention shown incross-section in FIG. 9 , the protrusion 17 is not formed prior to theinsertion of the anchor shank 8 but is formed by the underside 12 of theanchor head 9 at the end of the insertion of the anchor shank 8. Theanchor hole 6 is made in the flat underside 7 of the C-profile channel 2with a diameter of approximately 0.7 times the diameter of the anchorshank 8 outside the knurling 13 which, during insertion, widens theanchor hole 6 so that the C-profile channel 2 is seated clamped on theanchor shank 8. In FIG. 9 , as in FIG. 1 , the hole rim of the anchorhole 6 also engages between the knurling 13 forming the counter-bearing14 and the anchor head 9, is held clamped on the anchor shank 8 and isadditionally held by the anchor head 9 and the knurling 13 byinterlocking engagement. At the end of the insertion of the anchor shank8 through the anchor hole 6 of the C-profile channel 2, the anchor head9 is pulled and/or pressed by its underside 12 against the inner side ofthe underside 7 of the C-profile channel 2 and in so doing forms theoutwardly projecting protrusion 17 on the underside 7 of the C-profilechannel 2.

For insertion through the anchor hole 6, the anchor shank 8 of theexemplary embodiment from FIG. 9 is frustoconical at its end remote fromthe anchor head 9, whereas the anchor shank 8 in FIG. 1 has a chamfer atthe end remote from the anchor head 9 and the C-profile channel 2, onwhich end the anchor foot 21, 22 is then provided.

It is intended that the anchor channel 1 be concreted into, for example,a concrete ceiling (not shown) so that the upper side 5 of the C-profilechannel 2 having the longitudinal slot 4 is flush with a surface of theconcrete. The anchor(s) 3 arranged along the C-profile channel 2 atintervals in the longitudinal direction are likewise concreted into theceiling and, by means of their anchor feet 21, 22, hold the C-profilechannel 2, or the anchor channel 1 as a whole, in the base. Using, forexample, hammerhead screws, articles, such as, for example, a façadesubstructure, can be attached to the anchor channel 1 and accordingly tothe concrete ceiling (not shown). For that purpose, hammerheads of thehammerhead screws (not shown) are aligned in the longitudinal directionof the C-profile channel 2, introduced through the longitudinal slot 4in the upper side 5 of the C-profile channel 2 and, by rotation through90° or possibly even less, brought into engagement behind the upper side5 of the C-profile channel laterally of the longitudinal slot 4.

LIST OF REFERENCE SYMBOLS Anchor Channel and Method for Producing anAnchor Channel

1 anchor channel

2 C-profile channel

3 anchor

4 longitudinal slot

5 upper side

6 anchor hole

7 underside of the C-profile channel 2

8 anchor shank

9 anchor head

10 longitudinal side

11 transverse side

12 underside of the anchor head 9

13 knurling

14 counter-bearing

15 punch

16 deforming shoulder

17 protrusion

18 die

19 hole

20 depression

21 upset anchor foot

22 nut of the anchor foot

23 thread

1. An anchor channel having a C-profile channel, which has an anchorhole, and having an anchor, which has an anchor head and an anchor shankand which has been inserted through the anchor hole from the inside, sothat the anchor head is located in the C-profile channel and the anchorshank projects outwards from the C-profile channel, wherein the anchorshank has knurling spaced apart from the anchor head; a cross-section ofthe anchor shank is the same on both sides of the knurling; and a holerim of the anchor hole engages between the anchor head and the knurling.2. The anchor channel according to claim 1, wherein the hole rim of theanchor hole is seated clamped on the anchor shank between the anchorhead and the knurling.
 3. The anchor channel according to claim 1,wherein the anchor has a countersink head as anchor head; the C-profilechannel has an outwardly projecting protrusion that surrounds the anchorhole; and on an inner side of the C-profile channel the anchor head liesinside the outwardly projecting protrusion of the C-profile channel thatsurrounds the anchor hole.
 4. The anchor channel according to claim 1,wherein the C-profile channel has a slot in an upper side locatedopposite the anchor hole; and the anchor head is narrower and longerthan the slot is wide.
 5. A method for producing an anchor channelhaving a C-profile channel, which has an anchor hole, and having ananchor, which has an anchor head and an anchor shank and which isinserted through the anchor hole from the inside, so that the anchorhead is located in the C-profile channel and the anchor shank projectsoutwards from the C-profile channel (2), wherein during insertion of theanchor shank the anchor hole is widened by means of the anchor shank. 6.The method according to claim 5, wherein the anchor has on the anchorshank, spaced apart from the anchor head, a counter-bearing thatprotrudes beyond a circumference of the anchor shank, whichcounter-bearing overlaps a hole rim of the anchor hole on an outer sideof the C-profile channel.
 7. The method according to claim 5, whereinthe counter-bearing is in the form of knurling; and the hole rim of theanchor hole engages between the anchor head and the knurling.
 8. Themethod according to claim 6, wherein prior to the insertion of theanchor shank the diameter of the anchor hole is smaller than thediameter of the anchor shank between the anchor head and thecounter-bearing, so that the inserted anchor shank widens the anchorhole and is held clamped in the anchor hole.
 9. The method according toclaim 5, wherein the anchor hole is circular and the anchor shank has acircular cross-section; and prior to the insertion of the anchor shankthrough the anchor hole the anchor hole has a smaller diameter than theanchor shank.
 10. The method for producing an anchor channel accordingto claim 5, wherein the C-profile channel has an outwardly projectingprotrusion that surrounds the anchor hole, which protrusion is producedprior to the insertion of the anchor shank through the anchor hole, andthe anchor shank is then inserted through the anchor hole of theC-profile channel from the inside.
 11. The method for producing ananchor channel according to claim 5, wherein the anchor shank isinserted through the anchor hole of the C-profile channel from theinside, so that the anchor head is located in the C-profile channel;and, at the end of the insertion of the anchor shank through the anchorhole in the C-profile channel, an underside of the anchor head ispressed against the C-profile channel from the inside with sufficientforce that the underside of the anchor head forms an outwardlyprojecting protrusion of the C-profile channel that surrounds the anchorhole.